Wind power is considered one of the cleanest, most environmentally friendly energy sources presently available, and wind turbines have gained increased attention in this regard. A modern wind turbine typically includes a tower, a generator, a gearbox, a nacelle, and a rotor having a rotatable hub with one or more rotor blades. The rotor blades capture kinetic energy of wind using known airfoil principles. The rotor blades transmit the kinetic energy in the form of rotational energy so as to turn a shaft coupling the rotor blades to a gearbox, or if a gearbox is not used, directly to the generator. The generator then converts the mechanical energy to electrical energy that may be deployed to a utility grid.
Each rotor blade of a wind turbine typically includes a suction side shell and a pressure side shell formed using molding processes that are subsequently bonded together via adhesives at bond lines along the leading and trailing edges of the blade. The pressure and suction side shells are relatively lightweight and have structural properties (e.g., stiffness, buckling resistance and strength) that are not configured to withstand the bending moments and other loads exerted on the rotor blade during operation. Thus, to increase the stiffness, buckling resistance and strength of the rotor blade, the shells are typically reinforced using one or more structural components (e.g. opposing spar caps with a shear web configured therebetween) that engage the pressure and suction side inner surfaces of the shell halves. The spar caps are typically constructed of various materials, including but not limited to fiber-reinforced laminate composites including a thermoset resin. The shells of the rotor blade are generally built around the spar caps by stacking layers of fiber fabrics in a shell mold. The layers are then typically infused together, e.g. with a thermoset resin.
Such rotor blades, however, are not without issues. For example, the bond lines of typical rotor blades are generally formed by applying a suitable bonding paste or adhesive along the bond line with a minimum designed bond width between the shell members. These bonding lines are an important design constraint of the blades as a significant number of turbine blade field failures occur at the bond-line. Separation of the bond line along the leading and/or trailing edges of an operational turbine blade can result in a catastrophic failure and damage to the wind turbine.
In addition, the methods used to manufacture the rotor blades and/or structural components thereof can be difficult to control, defect prone, and/or highly labor intensive due to handling of the dry fabrics and the challenges of infusing large laminated structures. Moreover, as rotor blades continue to increase in size, conventional manufacturing methods continue to increase in complexity as the blade halves are typically manufactured using opposing mold halves that must be large enough to accommodate the entire length of the rotor blade. As such, joining the large blade halves can be highly labor intensive and more susceptible to defects.
One known strategy for reducing the complexity and costs associated with pre-forming, transporting, and erecting wind turbines having rotor blades of increasing sizes is to manufacture the rotor blades in blade segments. The blade segments may then be assembled to form the rotor blade. However, known joint designs for connecting the blade segments together typically have a variety of disadvantages. For example, many known joint designs require complex interconnecting components and do not provide for sufficient alignment of the blade segments, thereby increasing the amount of time needed to assemble the blade segments. In addition, segmented blades are typically heavier than conventional blades due to the additional joints and/or related parts.
Thus, the art is continuously seeking new and improved rotor blades and related assembly methods that address one or more of the aforementioned issues. Accordingly, improved wind turbine rotor blade components having varying fiber density regions that can be easily and effectively assembled would be welcomed in the technology.